drop-off(n = noun.process) falling off, falloff, slack, slump - a noticeable deterioration in performance or quality; "the team went into a slump"; "a gradual slack in output"; "a drop-off in attendance"; "a falloff in quality"
drop-off(n = noun.event) decrease, lessening - a change downward; "there was a decrease in his temperature as the fever subsided"; "there was a sharp drop-off in sales"